1. Field of the Invention
The present invention relates to a method of manufacturing a photo mask, and a method of manufacturing a semiconductor device using the manufactured photo mask.
2. Description of the Related Art
Recently, strict dimension accuracy has rapidly become required in photo masks; for example, the allowable range of dimension uniformity within the mask is less than 10 nm. In the photo mask manufacture, many items are given to determine whether the photo mask is a non-defective or defective product. In these items, if there exists even one item, which does not satisfy the specification, the photo mask has been conventionally determined as being a defective product. Therefore, the photo mask yield inevitably worsens under the present circumstances that the photo mask requires strict dimension accuracy.
Conventionally, the photo mask specification has been determined so that desired exposure latitude is obtained even if all of items are the lowest limit value satisfying the specification. However, in actually manufactured photo masks, it is extremely rare that all items have the lowest limit value satisfying the specification. In many cases, a certain item exceeds the specification value while other items are within an allowable range of the specification value with margins. For this reason, there exists photo masks satisfying the desired exposure latitude in photo masks disposed as defective product.
In order to solve the foregoing problem, JPN. PAT. APPLN. KOKAI Publication No. 2002-72440 discloses the following method. According to the method, exposure latitude is calculated based on the pattern dimension average value of the photo mask and the uniformity within the mask. From the calculation result, it is determined whether the photo mask is a non-defective or defective product. However, according to the method, it is possible to extract patterns having low exposure latitude, but it is difficult to extract portions potentially degrading the exposure latitude. Therefore, the method is not suitable for securely extracting a monitor portion used to determine whether the photo mask is non-defective or defective.
Conventionally, it is difficult to properly extract the monitor portion (dangerous portion) used to determine whether the photo mask is non-defective or defective. Therefore, it is desired to provide a method of manufacturing a photo mask, which can properly and readily determine whether the photo mask is non-defective or defective.